Fluid filled ear muffs



April 19, 1960 R. F. GRAY FLUID FILLED EAR MUFFS Filed Jan. 28, 1959 F/'g. 2 BY INVENTOR. REUBEN FLANAGAN GRAY 2,933,086 Patented Apr. 19,1960 FLUID FILLED EAR MUFFS Reuben Flanagan Gray, Levittown, Pa.,assignor to the United States of America as represented by the Secattary of the Navy Application January 28, 1959, Serial No. 789,755 9Claims. (Cl. 128-452) (Granted under Title 35, US. Code (1952),sec. 256)The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

The present invention relates to a fluid filled earrnufif, and moreparticularly, to a fluid filled earmuff which may be worn as aprotection against aerotitis caused by a pressure differential on theear drum.

More precisely, aerotitis is an inflammation or distortion of thetympanic membrane, or car drum, caused by the existence of a pressuredifferential between the middle and outer ear, and may occur duringrapid ascent or descent through an air or water medium. In certaininstances, the distortive effect may be extremely painful. While devicesexist in the prior art for the purpose of equalizing the pressurebetween the middle and outer car to thereby mitigate aerotitis, thenature of these devices is such that their use is generally incompatiblewith instrumentalities presently contemplated for increasing humantolerance to the effect of acceleration or deceleration forces. Thus,while prior art devices are generally satisfactory for theirspecifically intended purpose, they do not preclude the occurrence ofaerotitis when used with contemporary anti-blackout apparatus inaccelera: tion or deceleration environments.

The instant invention obviates the limitations of the prior art by meansof a novel type fluid filled earrnuff. In essence, the inventive deviceconsists of a pair of constant pressure, fluid filled, cup-like members,each of which fits tightly over the auricle of a subject. A fluid,preferably of isotonic character, occupies the closed space formed bythe interior of the cup-like member, external auditory canal, andtympanic membrane, or eardrum. Provision is included for varyingpressure upon the fluid and for the egress of air from the ear muff. Dueto the incompressible nature of the fluid in a constant pressurevolumerelationship, there is no tendency for distortion or displacement of thetympanic membrane. Hence, no

pain occurs in the absence of distortive effects due to ambient pressurechanges.

Thus, it is an object of the present invention to provide liquid filledear mufis which completely enclose the outer ear and maintain asubstantially constant pressure-volume relationship in the region oftheexternal auditory meatus, regardless of ambient pressure conditions.

Another object of the present invention is the provision of liquidfilled ear mufis which are characterized by a constant pressure-volumerelationship such that distortive effects upon the tympanic membrane areprecluded, irrespective of ambient pressure conditions.

Still another object is to provide ear muffs with liquid filling andpressure regulating means operable to vary the pressure of the liquidand expel entrapped air therefrom.

A final object of the instant device is to provide a means formaintaining the ear muffs in a secure position about the head of thesubject.

Other objects and advantages will become more fully apparent uponexamination of the annexed description and attached drawings, wherein:

Fig. 1 is a sectional view of a preferred embodiment of a single earmuff taken on line 1-1 of Fig. 2,

Fig. 2 is an elevation view of a pair of the inventive ear muffs as wornby a subject, showing an exemplary type of headband which may be usedfor maintaining the ear muffs fixedly secured about the subjects head,

Fig. 3 is an elevation view of a pair of the inventive ear muffs as wornabout the subjects head, showing a positive type of headband formaintaining absolute sealing and immobility of the ear muffs relative tothe subjects head, and

Fig. 4 is an enlarged elevation view of an ear muff, showing incross-section the adjustable tightening means used with the embodimentillustrated in Fig. 3. 7

Referring now to the drawings wherein like reference numerals designatelike or corresponding parts throughout the several views, there is shownin Fig. 1 a preferred embodiment of the ear muff assembly of the instantinvention, generally designated by reference numeral 10. Casing 12, acup-like member of metallic or other material having a rigidcharacteristic, is fixedly attached to scaling member 11 by conventionalmeans such as bonding or rivets, not shown. The inside dimensions ofcasing 12 are such as to permit fully enclosing the auricle. Member 11is a material such as rubber, or the like, capable of being deformed toaccommodate the contour of the portion of the head embracing thesubjects auricle. In order to provide absolute sealing consonant with ahigh degree of required immobility of the casing 12 relative to thehead, sealing member'll may be shaped especially to conform with theparticular contour of the subjects head in the region of the externalear.

The liquid filling apparatus, generally designated by reference numeral20 is threadably engaged into casing 12 at threaded aperture 13, asexemplarily shown in Fig. 1. Valve 24 is of a type preferably having twoseparate openings, which are aligned respectively with inlet pipe 22 andbleeder duct 23 in the open position of the valve. Manually operatedknob 21 controls valve 24. Duct 23 is fixedly attached by soldering, orthe like, to the inside of pipe 22, and performs a bleeding function,allowing air entrapped Within the liquid to be expelled during filling.Separate valves may be provided, of course, for independent controlof'the liquid supply and the bleeder functions. Apparatus 20 consistingof valves 24 and pipes 22 and '23, of course, may be entirely integrallyformed.

The piston assembly, generally designated by reference numeral 30 on earmuff or earpiece 10, is threadably engaged to casing 12 via threadedaperture 16. Rotation of knob 15 in either direction causes shaft 14-andits attached piston 17 to respectively enter or be withdrawn from theinner confines of casing 12. An 0 ring 15 on piston 17 provides a watertight seal on cylinder 19. In this manner, not only may the liquidpressure he varied'directly according to the particular requirements ofan antiblackout apparatus, but also, such means compensates forincremental changes in pressure and volume due to the softnesscharacteristics of body tissue.

Referring now to Fig. 2, wherein said inventive ear muffs are attachedand maintained secure about the external ear area of the subjects head,there is shown a relatively stiff leaf spring 41 connecting a pair ofear muff assemblies 10 by rivets 9, or the like. The resilient tendencyof spring 41 is such as to cause ear muffs 10 to be forced inwardlytoward the head, so that a positive seal may be "effected between thesealing members 11 and the subjects head. In order to assure positivesealing consonant with a high degree of immobility of earpiece 10relative to the head, leaf spring 41 may be one of a plurality of suchsprings, each of which may be consecutively angularly disposed from theothers in a fanlike arrangement.

- Referring next to Fig. 3, there is shown an elevation view of theinventive ear muffs as worn about the subjects head, utilizing in thisinstance a rigid type of-headband for maintaining absolute sealingconsonant with requisite immobility of the ear muff relative to the headof the wearer. The headband is comprised of an inflexible frame member40, the extremities of which are threadably engaged with adjustablepressure rods 43, such that a pressure comfortable to the wearer, andcommensurate with that required to effect sealing and immobility of theear muff assembly may be applied. Material 42 is provided for headcomfort and may be sponge rubber, or the like, which is fixedly securedto the inside of frame member 4%). Optional plugs 25 may be utilized, asshown, on ear muffs in lieu of assembly Zt), discussed in connectionwith Fig. 1. If desired, the entire ear muff assembly portrayed ineither Figs. 2 or 3, except for the pressureadjusting means in Fig.3,may be enclosed in a resilient media, such as rubber, or the like,to'provide absorption or cushioning of the ear muff against accidentalcontact with foreign objects.

Fig. 4 illustrates in partial cross-section the adjustable tighteningfeature of the instant invention. Pressure transmitting rod 43 isthreadably engaged with frame member 40. The shank portion 43A isslidably engaged for..limited movement within an aperture 44A in thebracket member 44, which is fixedly secured in a conventional manner tothe casing 12 of earpiece 10. A

pressure plate 45 is attached to the end of the shank, as illustrated,to thereby transmit a tightening pressure to casing 12. Thus, theearpiece 10 and bracket member 44 are disposed for displacement relativeto the rigid frame 40. I

With the ear muffs 10 comfortably secured to the subjects head, .fillingof eachear muff 10 with a liquid preferably having isotonic propertiesmay be started. In practice, water in distilled or undistilled. form isan excellent medium. Valve 24 is opened by rotation of knob 21, allowingliquid 50 to how preferably under influence of gravity from a sourcesuch as a reservoir, not shown. The liquid thus enters the interior ofthe earpiece through pipe 22, filling the closed space, formed by thecasing,

the tympanic membrane, and external auditory meatus of the subject.

Ambient air entrappedwithin earpiece 10 is expelled through pipe 23,during the filling process. -To insure that ambient air iscompletelybled off from the interior of the ear muff, including theregion of the external auditory meatus, the subject should move his headoccasionally during the filling operation. When all the entrapped air isexpelled, as evidenced by a continuous effiuxof the liquid medium fromduct 23, valve 24 is closed, shutting off both the liquid supply andbleeder tube. If desired, the assembly 2% may be thereupon removed and aplug inserted, as shown in phantom in Fig. 1 and by solidline in Figs. 2and 3.

A degree of adjustment is provided by piston assembly for regulating thepressure of the liquid confined Within the ear muff. Rotation of knob 15causes piston 17 to enter or be withdrawn from the inner confines ofcasing 12 by the action of screw threads 16 on threaded shaft 14. Thewatertight seal provided by O ring 18 and cylinder wall 19 prevents theloss of any liquid 50 therethrough. Hence, in this manner the pressuremay be adjusted in accordance with operational requirements ofcontemporary anti-blackout instrumentalities and personal comfort of thesubject; Piston assembly 36 also affords a feasible means forcompensating for incremental changes in'volume of the liquid due tosoftness characteristics in body tissue. V, 1 j. v The principle ofoperation of the instant invention is based uponphysical laws whichrelate to the behavior of incompressible fluids in a constantpressureevolume relationship. Consider the mechanism by which aerotitisis precluded in the instant invention when changes in ambient pressureoccur. Assuming the liquid filled ear muffs to be'securely in positionabout the head of the wearer, an increase in ambient pressure will bereflected through the subjects Eustachian tubes as an increase inpressure within the middle ear. The tympanic membrane or eardrum, wouldtend under normal circumstances, to be displaced outwardly from thecenter of the head. However, due to the incompressible nature of thefluid occupied within the interior space formed by casing 12 of the earmuff, the external auditory meatus, and the tympanic membrane, nodisplacement or distortive effect of the tympanic membrane occurs. Now,consider the case when the ambient pressure falls to a level lower thanthat of the liquid within casing 12. The decrease in ambient pressurewill be reflected through the Eustachain tube as a decrease in pressurewithin the middle ear, and the tympanic membrane in this instance wouldtend under normal conditions to be inwardly displaced toward the centerof the head. However, the distortive effects upon the eardrum are againprecluded under this condition, since the liquid within the interiorconfine of the ear muif assumes a pressure which acts oppositely on thetympanic membrane. The action is analogous to that observed when waterfilling a glass and covered by a sheet of paper, is apparently supportedby the paper when the glass is held upside down. Thus, in a similarmanner, the presence of an incompressible fluid within the closedinterior confine formed by the subjects tympanic'membrane, the externalauditory'meatus, and the casing proper of the inventive ear mufi,preyents displacement or distortion of the tympanic membrane when adecrease of ambient pressure occurs. Hence, irrespective of changes inambient pressure, aerotitis and its painful consequences are prevented.

In summary, the instant invention presents a novel approach in obviatingthe limitations of the prior art. The principle upon which the instantinvention is based resides in the applicability of physical lawsembracing the con stant pressure-volume relationship of anincompressible fluid. Thus, the instant invention not only precludesaerotitis and its painful consequences, but also, the inventive fluidfilled ear muffs are of a construction such that they are fullycompatible for use in anti-blackout systems of contemporary design.

Obviously, many modifications and variations of the present inventionare possible in the light of the above teachings. For instance, a,headphone devic not herewith shown,m ay be embodied within the casingofthe ear muff assembly to permit speech communication with a wearer ofthe inventive device. Such a headphone may be entirely encapsulated soas to be Water-proof. except for its diaphragm which transmits theauditory undulations through the liquid, a a a It is therefore to beunderstood that, within the scope of the appended claims, the inventionmay bepracticed otherwise than as specifically described. a

What is claimed is: a

1. A headgear device of the'type describedadapted for holding a liquidcomprising, a pair of cup-like members each having a bordering edge,sealing means attached to the bordering edge of each of the cup-likemembers, a headband means having opposite ends thereof respectivelyattached to each of the cup-like members,

liquid inlet means for said cup-like members, and bleeder means forexpelling entrapped air from within each of said cup-like members inoperable position of said headgear device.; l I 1; I

2. A'headgear device of the type described adapted for olding a liquid cmpr si g. a pa r of cup-li me bers each having a.. bordering. edge,sealing .means attached to the bordering edge of each of the cup-likemembers, a headband means having opposite ends thereof assaoserespectively attached to each of the cup-like members, liquid inletmeans for said cup-like members, and pressure regulating means foradjusting pressure of said liquid.

3. The headgear device of claim 2 in which the headband means includesat least one resilient spring member for supporting the headgear device.

4. The headgear device of claim 2 in which the headband means includes arigid frame member having extremities respectively attached in athreadable relation with each of the cup-like members.

5. A headgear device of the type described adapted for holding a liquidmedium comprising, a pair of cup-like members each having a borderingedge, sealing means attached to the bordering edge of each of thecup-like members, a headband means having opposite ends thereofrespectively attached to each of the cup-like members, liquid inletmeans for said cup-like members, bleeder means for expelling entrappedair from within each of said cup-like members in operable position ofsaid headgear device, and pressure regulating means for adjustingpressure of said liquid medium.

6. A headgear device of the type described adapted for holding a liquidmedium, comprising, a pair of cuplike members each having a borderingedge, sealing means attached to the bordering edge of each of thecup-like members, a headband means having opposite ends thereofrespectively attached to each of the cup-like members, liquid inlet andbleeder means for each of said cup-like members including a commonlyoperated valve for controlling entry of the liquid medium and expellingentrapped air from the cup-like members in operable position of theheadgear device, means for adjusting pressure of the liquid medium.

7. A headgear device of the type described adapted for holding a liquidmedium for protecting the tympanic membrane in a living subject havingan external auditory meatus comprising, a pair of cup-like members eachhaving a bordering edge, sealing means attached to the bordering edge ofeach of the cup-like members contiguous with a portion of the face ofsaid subject embracing the external auditory meatus, headband meanshaving opposite ends thereof respectively attached to each of thecup-like members, liquid inlet means for operably filling the interiorclosed space formed by each of the cup-like members, the externalauditory meatus, and tympanic membrane of said subject, bleeder meansoperable to expel entrapped air from said interior closed space, andpressure regulating means for adjusting the pressure of said liquidmedium.

8. A headgear device for protecting the tympanic membrane in a livingsubject having an external auditory meatus against distortive' effectsdue to the rapid changes in ambient pressure comprising, a pair ofcup-like members each having a bordering edge, sealing means attached tothe bordering edge of each of the cup-like members adapted in use to becontiguous with a portion of the face of said subject embracing theexternal auditory meatus, headband means having opposite ends thereofrespectively attached to each of the cup-like members, liquid inletmeans for said cup-like members, the interior closed space of saidheadgear device formed in use by each of the cup-like members, theexternal auditory meatus, and tympanic membrane of said subject adaptedto be filled with a liquid fluid, bleeder means operable to expelentrapped air from said interior closed space, and pressure regulatingmeans for adjusting the pressure of said liquid fluid when said headgeardevice is in use.

9. A headgear device adapted for holding a fluid for protecting thetympanic membrane in a living subject having auricles and externalauditory meatus associated therewith comprising, a pair of cup-likecasing members each having a bordering edge and shaped generally tofully enclose each of the auricles of said subject, sealing meansattached to the bordering edge of each of the cuplike members adapted inuse to be contiguous with a portion of the face of said subjectembracing each of the auricles, headband means having opposite endsthereof respectively attached to each of the cup-like members, fluidinlet means for operably filling the interior closed space of saidheadgear device formed in use by the cup-like members, the externalauditory meatus, and tympanic membrane of said subject, and pressureregu lating means for adjusting pressure of said fluid when saidheadgear device is in use.

References Cited in the file of this patent UNITED STATES PATENTS989,839 Fowler Apr. 18, 1911 2,899,683 Wadsworth et al Aug. 18, 1959FOREIGN PATENTS 467,298 Germany Aug. 27, 1927 565,986 Germany Dec. 9,1932 792,059 Great Britain Mar. 19, 1958

